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Mysterious Oil Consumption? Change your PCV Valve!

Job location changed and I ran two quarts low all of a sudden *(over six months) when I began driving 30 minutes round-trip per day at speeds of 65-75 mph at 3k+rpm. I NEVER had a problem with oil consumption over same milage/time interval traveling surface streets to work -the Subie shop would have mentioned it, right?

I'm back to surface streets, new job location, same milage/time interval and have added 1/2 quart over past six months to keep it topped up.

Sure, NOW I check my oil at each fill up.

Sure, NOW I'm going to replace the PVC valve.

Sure, NOW I'm going to ask the Subie dealer, 30+ oil changes and 100,000 miles since new, why they have never mentioned PVC valve.

I have never believed in 3,000 mile oil changes. I peg it at 5,000.

When is the best time to check oil level? Stone cold? Fire hot? Luke warm? I get different readings between the notches/holes at different temps.

I always check first thing in the morning before the car is started for the day.
This allows the oil to settle into the pan overnight, and ensures the oil level will be accurate. After the engine has been running a lot of oil is still in the heads and dripping down from the block.
If you check the oil level immediately after turning the engine off, then check again an hour later you will get different readings as the oil settles out of the crank-case back down into the pan.

I helped a friend out some time ago with his Loyale that was blowing so much smoke out the tail pipe is was like going through a smoke screen. Fortunately he had a new spare PCV valve in the garage. We changed it out to see if that worked and then there was no more smoke. Easy fix.

- Last attempt ran the Gunk Engine cleaner at idle for about 30 minutes (way longer the specified on the instructions) as it worked I could hear the engine change. So far so good, 200 miles and no oil usage, no smoke. Only 154K on the motor with new HG due to the bent valves of the timing going for the PO. I usually would not use the Internal "Cleaners" but I was down to pulling the engine apart so nothing to loose.

My 98 forester with frankenmotor and new seals was using 1 qt a week. i was able to reduce consumtion to 1 qt every 2 weeks by replacing the PCV valve, until the ring land broke. i'm sure the oil was being used past the rings as well, but the PCV did help a lot in that regard.

I have had success rejuvinating old oem PCV vlves by sea foaming them.

I work at an oil change shop, and some later model cars come in with low oil at 3000 miles, and these are cars with moderate miles, and unserviceable PCV's. I noticed toyota uses the same type of pcv, but unfortunately, our shop doesn't stock this type of PCV valve.

And with failed pcv valve in mind, there are some late model engines coming in with 'rear main seal leaks', and i would bet suggesting a PCV valve would help that.

Our 2012 Outback has consumed oil excessively since the day we got it. (excessive = 1.3 qt/1200 miles) This is many times more than any car we or any extended family have ever owned, which is dozens of cars and at least 10 manufacturers. The dealer has insisted that "up to 1qt/1200 miles is normal and as-designed. Lousy design.

I don't know if they ever checked the PCV or rear separator plate (I'll ask tomorrow), but they now have offered the following: "We will install a new valve cover, inside of which there are a series of baffles. These keep the normal oil inside the of the valve cover from getting to the PCV valve, but Subaru has found some oil getting past one of the baffles allowing the PCV to pick up the oil. The new valve cover is supposed to keep that from happening. The new part number is 13728AA291"

I don't know if anyone else has experience with this, but I'm interested in any info.

... Subaru has found some oil getting past one of the baffles allowing the PCV to pick up the oil. The new valve cover is supposed to keep that from happening. The new part number is 13728AA291 ...

In the Old School Subarus, something similar happened with the EFi Subaru EA82 Engines, and they then sold a Re-Routing Kit for the PCV System, in order to avoid the PCV Valve to Suck oil; let me share a Post here, taken from Another thread:

...certain EFI EA82's also has problems with their PCV System Sucking Oil,

I'm glad this thread was revived. Noticed my oil was lower than normal yet no external leaks. PCV was the only thing that wasn't replaced when the car was purchased last year. Also getting erratic idle. Will have to check if it's clogged.

FWIW, oven cleaner with lye will remove any and all oil deposits (even varnish off the metal which brake cleaners won't) including heavy sludge. Spray in, let it set for several minutes, then spray out with water. Dry immediately. Might need to do a second time if the oil is coked really bad and use a pipe cleaner to hasten the job. Best thing is the generic oven cleaners are $2 a can at Giant Eagle. As long as the cleaned valve permits flow in the one direction and not the other, it should still be usable. (Disclaimer: lye is VERY caustic to the skin and can cause burns. Should avoid breathing the vapors as well. It's excellent at cleaning cast iron and steel, but will dull polished aluminum.)

After finding this thread, I replaced my PCV valve on my 2009 Impreza several months ago. I bought this car new and from early on I was getting excess oil consumption and the smell of oil while driving but could not find any sign of an oil leak. My old PCV was not oily and you could hear the movement inside the valve when you shook it. I replaced it anyway since it was out and I had the new one in hand. Since I replaced it, I no longer have the smell of oil while driving. I believe my oil consumption was reduced as well, but I still have to add oil between changes.

Our 2012 Outback has consumed oil excessively since the day we got it. (excessive = 1.3 qt/1200 miles) This is many times more than any car we or any extended family have ever owned, which is dozens of cars and at least 10 manufacturers. The dealer has insisted that "up to 1qt/1200 miles is normal and as-designed. Lousy design.

I don't know if they ever checked the PCV or rear separator plate (I'll ask tomorrow), but they now have offered the following: "We will install a new valve cover, inside of which there are a series of baffles. These keep the normal oil inside the of the valve cover from getting to the PCV valve, but Subaru has found some oil getting past one of the baffles allowing the PCV to pick up the oil. The new valve cover is supposed to keep that from happening. The new part number is 13728AA291"

I don't know if anyone else has experience with this, but I'm interested in any info.

Thanks

Is your Outback the 6 cylinder model?

My family's 2011 3.6 has been burning oil lately, but usually only under stress: i.e. two road trips with the car loaded.

They had showed a (I believe valve cover plate) and how dirty it was, whichever piece it was, they insisted it had tiny channels for some sort of valve that can get clogged up.

Now that I think about it, it was to the Crankcase, so PCV it must be.

On two occasions, the head mechanic pulled one of these clogged plates from a pile lol, and spewed what we took as rubbish.

They insisted a "proper" oil maintenance schedule should be followed with something like once every 3,000 miles for these 6 cylinders. Otherwise the plates get gunked up and you know the rest, as for simply reconditioning/cleaning the plate, I was told and shown by the mechanic that's been there for years, that it's quite impossible to clean, and the channels are riveted into the plate... non-removable by their standards.

What I took from this, is the covers do have a pseudo-design flaw, we have been adhering to their oil schedule just to ensure warranty coverage, 5k is what we went with for the first few oil changes (besides the very first).

Hudsonfamily, my family just drove to FL from the midwest and had the car checked at a dealer down there. I'll find out how "our's" is doing, but above all else, KEEP BUGGING THE DEALER and get as many records of these issues as you can early on.

As long as the cleaned valve permits flow in the one direction and not the other, it should still be usable.

Not always true. I've seen enough clean and free (still rattle) PCV valves cause oil consumption problems that I just replace them if they're heavily sludged. I only clean them as a preventative matter. If they're plugged, I replace them when viable.

Not always true. I've seen enough clean and free (still rattle) PCV valves cause oil consumption problems that I just replace them if they're heavily sludged. I only clean them as a preventative matter. If they're plugged, I replace them when viable.

Not sure how elaborate these valves are as opposed to other cars, but it's designed to only allow flow in one direction. As long as it's working correctly, it can be reused.

Also, you can get oil consumption with a brand new PCV. Turbo cars are more prone (in general). If oil makes it's way pass the valve cover baffling and get's into the hose, it can over time get sucked into the intake and down into the throttle body. Best bet if it's happening a lot is to install a catch can OR have a drain back device installed, though the catch can is better as you aren't risking contaminants getting drained back. Some engines have less than ideal PCV systems.

While changing my pcv valve I noticed the hose's were caked in sludge. Still enough to breathe, but clogging for sure. I managed to clean the longer hose but this Y connector (picture) would not come off the engine. I didn't want to scrape the sludge back into the crankcase... So what do I do?

The large hose on that one usually breaks (after you break the Y part first). Last one I did I had a heck of a time finding emissions hose that large. Ended up cutting up an old IAC hose.
Literally had to chisel the old hose off the fitting on the block. The hose broke off at the bottom and left the last inch or so on the block. The thing was brittle as glass.
I was able to get a small pick in around the Y fitting and the hose broke around that too and I was able to get the Y out without breaking it. A little silicone grease in the new hose and it all went back together easy.

The large hose on that one usually breaks (after you break the Y part first). Last one I did I had a heck of a time finding emissions hose that large. Ended up cutting up an old IAC hose.
Literally had to chisel the old hose off the fitting on the block. The hose broke off at the bottom and left the last inch or so on the block. The thing was brittle as glass.
I was able to get a small pick in around the Y fitting and the hose broke around that too and I was able to get the Y out without breaking it. A little silicone grease in the new hose and it all went back together easy.

That's what I'm afraid of doing! I practiced at the junkyard and I couldn't get it out of the block without breaking it..

Can I just get a bottle brush and some seafoam and go to town on it? Then do an oil change immediately? Or would the chunks remain in the crankcase?